Vehicle-pedestrian incidents often occur at intersections where a pedestrian is crossing the street during a WALK interval.
Source: Gina Coffman (2012)

A LPI allows pedestrians to be fully in the crosswalk before motorists attempt to turn.

Leading Pedestrian Interval

LPIs can be programmed into traffic signals to minimize conflicts between pedestrians crossing a roadway and left or right turning vehicles. LPIs give the pedestrian the WALK signal 3-7 seconds before the motorists are allowed to proceed through the intersection.20

By giving pedestrians a head start, it is less likely that there will be conflict between pedestrians and turning vehicles. LPIs increase the percentage of motorists who yield the right of way to pedestrians because pedestrians are in the crosswalk by the time the traffic signal turns green for parallel vehicle movements.

Purpose

Vehicle-pedestrian incidents often occur at intersections where a pedestrian is crossing the street during a WALK interval. Pedestrians are especially vulnerable to left turning vehicles. Leading pedestrian intervals (LPIs) give pedestrians time to establish their presence in the crosswalk before motorists can start turning.

Considerations

• If an intersection has particularly high pedestrian traffic, you might consider adding an exclusive pedestrian phase instead of a leading pedestrian interval.
• Make sure that the LPI is accompanied by an audible noise that lets visually impaired pedestrians know that it’s safe to cross.
• Keep in mind that right turn on red rules might limit the effectiveness of LPIs. Consider restricting right turn on red use at intersections.

Estimated Cost

The cost to alter the timing of a pedestrian signal can be relatively inexpensive (from $0 to $3,500), depending on the site specifications and the size of the city. Installing a new signal can range from $40,000-$100,000.

Safety Effects

A summary of studies that have looked at the safety effects of devices using a leading pedestrian interval can be found here.